425 - Too Early

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What Does Too Early Mean?

The server rejected an early-data request to avoid replay risk, so the operation must be retried through a safer handshake path.

Common Causes

• -CDN sends 0-RTT early data to non-idempotent POST /payments endpoint protected by replay-risk policy.
• -Client library reuses TLS session and transmits Early-Data: 1 to route explicitly configured as anti-replay.
• -Edge rule permits early data only for GET and HEAD methods, rejecting mutating requests during resumption.

How to Fix Too Early

1. 1Disable early data (0-RTT) for replay-sensitive requests, especially non-idempotent mutations.
2. 2Retry the same request after full handshake completion without early-data transport.
3. 3Add idempotency keys for mutation APIs that may still encounter network-level retries.

Step-by-Step Diagnosis for Too Early

1. 1Capture TLS/session details to determine whether request arrived via early data path.
2. 2Identify endpoints rejecting replay-prone requests and classify by idempotency safety.
3. 3Inspect intermediary behavior that might add or preserve Early-Data signaling unexpectedly.
4. 4Retest with early data disabled and verify safe retry behavior for affected operations.

curl -i -X POST https://api.example.com/v1/resource -H "Early-Data: 1" -H "Content-Type: application/json" -d "{"sample":true}"
# Response:
# HTTP/1.1 425 Too Early
# {"error":"Too Early","code":"425"}

const response = await fetch('https://api.example.com/v1/resource', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json', 'Accept': 'application/json', 'Early-Data': '1' },
  body: JSON.stringify({ sample: true })
});
if (response.status === 425) {
  console.error('Handle 425 Too Early');
}

import requests

response = requests.post(
    'https://api.example.com/v1/resource',
    headers={'Accept': 'application/json', 'Content-Type': 'application/json', 'Early-Data': '1'},
    json={'sample': True}
)
if response.status_code == 425:
    print('Handle 425 Too Early')

Seen in Production

Debugging Tools

• -TLS session and early-data telemetry
• -Idempotency-key and duplicate-operation logs
• -Client retry trace instrumentation
• -Ingress handshake mode diagnostics

How to Verify the Fix

• -Repeat affected calls with early data disabled and confirm 425 no longer appears.
• -Validate replay-sensitive endpoints reject unsafe early-data requests while allowing safe retry path.
• -Monitor duplicate-operation and retry metrics to confirm idempotency protections hold.

How to Prevent Recurrence

• -Define explicit policy: allow early data only for idempotent/read operations.
• -Enforce idempotency keys and replay guards on all critical mutation endpoints.
• -Add transport-level integration tests for TLS resumption and early-data edge cases.

Pro Tip

Related Errors

Official References

• -RFC 8470 Section 5.2 - 425 Too Early definition
• -IANA HTTP Status Code Registry - 425 Too Early
• -MDN Web Docs — 425 Too Early
• -HTTP Official Documentation